Parasites Flashcards
What are the main protozoa causes of GI infection?
Giardia lamblia
Entamoeba histolytica
Cryptosporidium
How does Giardiasis present?
bloating, flautlence, foul-smelling fatty diarrhea (often seen in campers and hikers) and is transmitted via cysts in contaminated water
How is Giardiasis tx?
metronidazole
How is Giardiasis diagnosed?
Trophozoites or cysts in stool
Entamoeba histolytics is the cause of _______
Amebiasis
How does Amebiasis present?
bloody diarrhea (dysenery), liver abscess (anchovy oasta exudates), RUQ pain, and histology showing a flask-shaped ulcer
How is Ambeiasis contracted?
cysts in water
How is Amebiasis diagnosed?
Serology and/or trophozoites (With RBCs in the cytoplasm) or cysts (with up to 4 nuclei) in stool
How is Amebiasis tx?
Metronidazole
iodoquinol for asymptomatic cyst passers
What parasite is known to cause severe diarrhea in AIDs pts and mild disease (watery diarrhea) in immunocompetent hosts?
Cryptosporidium
How is Cryptosporidium diagnosed?
oocysts on acid-fast stain
How is Cryptosporidium tx?
prevention by filtering water supplies and nitazoxanide in immunocompetent hosts
What protozoa cause CNS infection?
Toxoplasma gondii
Naegleria fowleri
Trypanosoma brucei
What disease does Toxoplasma gondii cause?
1) Congenital toxoplasmosis with a classic triad of chorioretinitis (below), hydrocephalus, and intracranial calcifications
2) Reactivation in AIDs- ring enhancing lesions on CT/MRI
Reactivation of Toxo in AIDs- ring enhancing lesions on CT/MRI
How is toxo transmitted?
cysts in meat (most common); occysts in cat feces
crosses the placenta (pregnant women should avoid cats)
How is toxo diagnosed?
Serology
or biopsy showing tachyzoites or bradyziotes
How is toxo tx?
Sulfadiazine and pyrimethamine
What disease does Naegleria fowleri cause?
Rapdily fatal meningoencephalitis
How is Naegleria fowleri transmitted?
swimming in freshwater and enters via the cribriform plate
How is Naegleria fowleri tx?
Ampho B (will likely die though)
What parasite causes African Sleeping sickness?
Trypanosoma brucei
How does African Sleeping sickness present?
enlarged lymph nodes, recurring fever due to antigenic variation, somnolence, and coma
What is the reservoir of Trypanosoma brucei?
tsetse fly, a painful bite
How is Trypanosoma brucei diagnosed?
blood smear
How is African sleeping sickness tx?
Suramin for blood borne disease or melarsporol for CNS penetration
melatonin for sleep
What protozoa cause hematologic infections?
Plasmodium (P. viva.ovale, falcoparum, and malariae)
Babesia
Plasmodium is the cause of ______
Malaria
What are the primary symptoms of malaria?
fever, HA, anemia, and splenomegaly
What is the vector for Plasmodium?
Anopheles mosquito
How does P. vivax/ovale induced malaria present?
48 hr cycle (tertain; includes fever on first day and third dayl thus fevers are actually 48 hrs apart); dormant form (hypnozoite) in liver
How does P. falciparum induced malaria present?
severe; irregular fever pattern, parasitized RBCs occlude brain capillaries (cerebral malaria), kidneys, and lung
How does P. malariae induced malaria present?
72 hr cycle (quartan)
How is malaria diagnosed?
blood smear- trophzoite ring form within RBC (below)
Schizont containing merozoites
red granules (Schuffner stippling) throughout RBC cytoplasm seen with P. vivax/ovale
Malaria- Schizont containing merozoites
How is malaria tx?
Chloroquine for sensitive species (blocks Plsmodium heme polymerase)
If resistant, use mefloquine or atovaquone/proguanol
If life threatening, use IV quindine or artesunate (test for G6PD deficiency)
For P. vivax.ovale, add primaquine for hyponozoite (test for G6PD deficiency)
Babesia causes Babesiosis. How does this present?
fever and hemolytic anemia, predominantly i the northEASTERN US (asplenia increases the risk for disease)
What carriers Babesia?
Ixodes tick (same as Lyme disease- may often coinfect)
How is Babesia diagnosed?
blood smear (ring form or Maltese cross)
PCR
How is Babesia tx?
Atovaquone and azithromycin
What protozoa cause visceral infections?
Trypanosoma cruzi
Leishmania donovani